1. Department of Social Medicine, School of Medicine, Federal University of Rio Grande do Sul Porto Alegre, Brazil
2. Division of Epidemiology, University of Mississippi Medical Center Jackson, Mississippi
3. Department of Preventive Medicine, University of Mississippi Medical Center Jackson, Mississippi; the National Heart, Lung and Blood Institute, Bethesda
4. Welch Center for Prevention, The Johns Hopkins Medical Institutions Baltimore, Maryland
5. Epidemiology and Clinical Research, The Johns Hopkins Medical Institutions Baltimore, Maryland; and the Department of Epidemiology, School of Public Health, University of North Carolina, Chapel Hill, North Carolina